在servlet-2.3中，Filter会过滤一切请求
转自：http://www.iteye.com/problems/61651

在servlet-2.3中，Filter会过滤一切请求，包括服务器内部使用forward转发请求和<%@ include file="/index.jsp"%>的情况。
到了servlet-2.4中Filter默认下只拦截外部提交的请求，forward和include这些内部转发都不会被过滤，

在要weblogic8.1，servlet2.3下让filter不要拦截内部转发的请求,可以让Filter扩展OncePerRequestFilter. 实现只处理外部请求

以下代码在weblogic8.1测试通过
<!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
<description>
Servlet and JSP Examples.
</description>
<display-name>Servlet and JSP Examples</display-name>

<filter>
<filter-name>first</filter-name>
<filter-class>filters.TestFilter</filter-class>
</filter>
<filter>
<filter-name>first1</filter-name>
<filter-class>filters.TestFilter1</filter-class>
</filter>

<filter-mapping>
<filter-name>first</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>first1</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

</web-app>


package filters;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;


/**
* 直接实现 Filter
* 默认过滤 forward和include 内部请求
* @author mojiezhong05180 2012-06-08
*
*/
public class TestFilter implements Filter {

private static int count = 0;

public void destroy() {
}

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
System.out.println((count++));
chain.doFilter(request, response);
}

public void init(FilterConfig arg0) throws ServletException {
}

}


package filters;

import java.io.IOException;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.filter.OncePerRequestFilter;

/**
* 扩展OncePerRequestFilter
* 只拦截外部提交的请求，forward和include这些内部转发都不会被过滤
* @author mojiezhong05180 2012-06-08
*
*/
public class TestFilter1 extends OncePerRequestFilter {

private static int count = 0;

protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws IOException, ServletException {
System.out.println("<TestFilter1>" + (count++));
filterChain.doFilter(request, response);
}

}

2012年6月08日 10:40